package com.dong.dao;

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

public class BaseDao {
    private static String driver;
    private static String url;
    private static String user;
    private static String password;

    //静态代码块，类加载的时候就已经初始化了
    static {
        Properties properties = new Properties();
        //通过类加载器获取想要获得得到资源
        InputStream is = BaseDao.class.getClassLoader().getResourceAsStream("database.properties");
        try {
            properties.load(is);
        } catch (IOException e) {
            e.printStackTrace();
        }

        driver = properties.getProperty("driver");
        url = properties.getProperty("url");
        user = properties.getProperty("user");
        password = properties.getProperty("password");
    }

    //获取数据库连接
    public static Connection getConnection(){
        Connection connection = null;
        try {
            Class.forName(driver);
            try {
                connection = DriverManager.getConnection(url,user,password);
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return connection;
    }
    //编写公共查询类
    public static ResultSet execute(Connection connection,PreparedStatement preparedStatement,ResultSet resultSet,String sql,Object[] params) throws SQLException {
        preparedStatement = connection.prepareStatement(sql);
        for (int i = 0;i < params.length;i++){
            preparedStatement.setObject(i+1,params[i]);
        }
        resultSet = preparedStatement.executeQuery();
        return resultSet;
    }

    //编写增删改公共类
    public static int execute(Connection connection,PreparedStatement preparedStatement,String sql,Object[] params) throws SQLException {
        preparedStatement = connection.prepareStatement(sql);
        for (int i = 0;i < params.length;i++){
            preparedStatement.setObject(i+1,params[i]);
        }
        int updateRows = preparedStatement.executeUpdate();
        return updateRows;
    }
    //释放资源
    public static boolean closeResource(Connection connection,PreparedStatement preparedStatement,ResultSet resultSet){
        boolean flag = true;
        if(resultSet != null){
            try {
                resultSet.close();
                resultSet = null;
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                flag = false;
            }
        }
        if(preparedStatement != null){
            try {
                preparedStatement.close();
                preparedStatement = null;
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                flag = false;
            }
        }
        if(connection != null){
            try {
                connection.close();
                connection = null;
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                flag = false;
            }
        }

        return flag;
    }


}
